if I have the function scopy that copies a C String from src to dest
char * scopy(char *dest, char *src) {
char* r = dest;
while (*src != '\0') {
*dest = *src;
dest++;
src++;
}
*dest = *src;
return r;
}
Why does this function work when called on 2 String initialized like this char a[6] = "abbbb" and char b[4] = "dcd" but doesn't work on Strings initialized like this char * a = "abbbb" and char * b = "dcd"
This function invokes undefined behavior when used like that because it tries to modify a string literal, so you can't say it works in either case.
The fact that it appears to work on the char[] is a coincidence -- an unfortunate one, because it gives the wrong impression.
In the code below, variable ptr is pointing to a read-only memory section, which contains "xyz\0". You can change the variable itself, but you can't change the contents of the memory it is pointing to...
char* ptr = "xyz";
In the code below, variable arr is pointing to a read/write memory section, which contains "xyz\0". You can't change the variable itself, but you can change the contents of the memory it is pointing to...
char arr[] = "xyz";
The above should help you to understand why you are getting a segmentation fault in the first case...
Having said that, you have yet another problem in your code - if the string pointed by src is longer than the string pointed by dest, then *dest = *src will most likely cause a segmentation fault:
while (*src != '\0')
{
*dest = *src;
dest++;
src++;
}
char*a = "abbbb" is called a string literal, which iirc behaves differently than a char[] in c. Specifically, I do not believe you can modify the individual characters for a string literal.
Try looking here for more information between the two constructors
